Take a look at this...
You may need to justify it over more than one job.
Or something like this will help
Also, I use these instead of DA300. The ER11 collet works better in a milling application
Here is what I did and it failed. I drilled and reamed one end .250", Leaving .5" of stock undrilled. Then I flipped it over drilled for the set screw and then drilled and reamed to .1250" and turned the stock down to .5000 in the same chucking ( 3 jaw chuck)and guess what, there was .009 TIR on the cutting tool when I indicated it. I suspect that maybe the center of the .250 hole was off and cause he drill and reamer for the .125 hole to be off? Go figure. When I gave up on that I got back to using the drill chuck and the results were not all that bad. I got the job done and if this turns into more work I will be buying the ER11 collet holder off of Mari tool. Maybe I am not quite a tool maker.
Maybe I'm missing something in the MM's description of the order of operations. In a three jaw, no matter how worn, if you drill and reamed or bored for the endmill shank o.d. and then turned down the o.d. of your extension, they'd have to be concentric. Why did you need to remove and re-chuck the piece? All you needed to do was cut it off and drill and tap a hole perpendicular for the setscrew.
Lol i did it limy Sami's way not to long ago, The run out is easy to adjust, using a high tech old fasioned non cnc device, Its called a hammer! Run out can be brought into line faster than i originaly thought would be possible.
I bored it from the other end so I can use the double end mills I have. WHY TF you bother, I don't know?
MM, he said take a piece and drill/ream the hole for the EM first, however deep it needs to be. Then turn the OD and part off. Drill and install a set screw to hold the EM. If you do the above in that exact order, and you aren't hanging the material out 3 inches from the chuck, it'll come out concentric. If you are having troubles with this procedure, make certain you use a center drill to start the hole, then a .120 stub drill, then a chucking reamer held as far from the business end as possible.
Only turn the portion you will grab in the holder, don't turn the entire length.
I don't see anything wrong with providing a runout hole as you did. I think others may not have read your procedure carefully enough.
In fact a runout hole is a good idea for chip clearance and to allow the reamer pilot to run into open air instead of bottoming.
(Esp if your reamer is a hand reamer which has a long tapered pilot)
I don't think any eccentricity in that runout hole would be telegraphed through to the 'proper' hole, but if that was a worry you could make the runout hole flat bottomed.
Assuming you checked the runout on the shank when checking the runout of the cutter at 0.009", and the former was negligible in comparison, I suspect it's the procedure you're using to drill the hole. As Perry says, a centre drill is essential (and watch the tip as it re-enters- if it deflects to one side, the tailstock needs to be realigned)
Stub drill (preferably split point, and freshly sharpened to a high standard) is also worthwhile to follow. Don't crowd the feed, and peck it to keep chips clear.
There are other ways of drilling true holes, but the procedure given is the safest & simplest, IMHO.
Unless we've a language problem, a lot of folk have missed the major part of my original post;-
I put the word bore in caps to emphasize it's importance,....... by bore I mean single point, drill, bore (single point) & ream was the sequence of operations.
Originally Posted by Limy Sami
That way the cutter bore and extension mount will be as concentic and true as the lathe.
Limy, good point, look at jig borers. If drill/ream was sufficient they wouldn't exist.
Sami's method is quick, easy and as accurate as can be achieved in a common shop. His description short and accurate, his patience, well... uh, same as for his description....
Boring bar the toughest part, tiny, sub .100- gotta' have a projecting point, sub .125" drilled hole and chip clearance. Maybe not really easy to make, but as a potential multi-use tool, the trouble might be justified. Using it successfully, well, trying at best. It's importance, high, for TIR, reaming does NOT center. Don't expect a hardened finished product. Pre-hard, forget that flimsy boring bar, post hardening, unacceptable distortion too often to mess with... START with drill/bore, no need for finish OD on scrap....
Making boring bar sequence: turn reduced, sub .100" portion of drill rod, heat and forge an off-set on the end. Heat treat. Use microscope while grinding off-set glob into a fine cutting edge..... hone with...
I do have a few in the drawer that would work, laboriously hand ground from square lathe bits... can be done... Turning drill rod maximizes the supporting shaft.
Any rechucking and subsequent altering of the chucking OD or holding ID makes (s)crap unless you've got something like a very good second-op lathe/collet and even then, holding acceptable TIR for a tiny endmill might be impossible.
I have a few straight shank collet holders and for this, I'd use my 1/2" shank, Universal Eng. WO collet holder, which I have dozens of tiny collets for, a bag full, cheap at auction..... I don't believe these are still in production, a great suggestion above is the ER 11 series, DA too, watch ebay.
I'm reserving (W)TF for "drill chuck"? ...but only 'cause I tried it...long ago...called "experience"....
Put that collet holder in a collet! Save that drill chuck for...guess.. clue in the name...
Originally Posted by Robert Campbell Jr.
Um.............he is drilling and boring a .375 hole, most HSS .125 endmills have a .375 shank :-). Any high school metal shop whiz can hand grind a tool to bore a .375 hole :-).
woah woah, I have .125 stub length end mills the shank is .125" how do I make a boring bar for that? Now to make the hole for the tool I started with a spotting drill then I went to a screw machine drill cleaned teh hole with 2 drills before I went to .125" reamer. anyways, whne I index the tool to the point where teh set screw is that is where my TIR is at the highest. I'm stumped.
A 3/32", 7/64", or 34mm endmill makes a nice boring bar for a 0.125" hole.
Originally Posted by madmachinst
Hey mad, some folks just mentally substitute what they feel would be best, like Willbird. He's got a good point, even if it is about a different tool shank than you're talking about, by 300% diameter, much more in cross section.
Originally Posted by madmachinst
A collet chuck that would hold a 3/8 shank, would be much bigger than the WO double taper collet chuck I mentioned above, just didn't want to "suppose" you had the room......
If you do, it might be a better choice but not 300% better, gotta narrow down to 1/8th somewhere and your "stub length" knocks out most over-sized shanks, while the fat collets obscure the cut from view.
Hey, if 3/8 is better, how 'bout 3/4"?... rare down on 'er... git 'er done... talk about easy to bore...
Don't be stumped, find a nice little collet chuck, here's the one I mentioned above, on the right. The one on the left has Willbird's 1/8 X 3/8 endmill in it. It's shank fits the bore of my Index Vertical mill. Instead of that combo, I'd have the small WO, straight shank collet chuck in it, which is wearing the appropriate Z collet for the big 'un.
You choose.... notice, no drill chuck....
"most HSS .125 endmills have a .375 shank"
Most of the *HSS* 1/8" endmills I've seen have 3/16" shanks. Carbide, 1/8".
Nice to find a 3/8" shank for this sort of thing, but in my world they were few and far between (box o' junk to pick thru most of the time).
I'm using pure carbide and I want to keep that flute length to a min so I don't get too many snapped e mills.
That revelation won't come as a big surprise John, (guessing "pure carbide" means solid TC) to the several posters above who have suggested the most cost effective and best suited class of tool, which MSC and many others could have had on the way to your mailbox by now.
Originally Posted by madmachinst
Enco, Shars and 800 watt's cheap stuff gotta beat the hell out of whittling a DIY cludge and I'm a dedicated whittler.
Heck, you might even have had a bargain ebay steal or "tools wanted" find, right here, on the way by now........my WO cost me 5 bucks...
Did you bother with this?:http://business.shop.ebay.com/i.html...&_osacat=92084
I'm poorly retired and this wouldn't break my bank:http://cgi.ebay.com/New-D25-100L-Str...#ht_1953wt_941 even smaller available, look...
Waiting for something to be invented, that's better suited to your published needs than a small collet chuck may take, well, a while... got the time?
for the price of what it costs on flea bay there is no way I am making my own.